.../testing/sysfs-driver-typec-displayport | 10 +++++++ drivers/usb/typec/altmodes/displayport.c | 28 +++++++++++++++++++ 2 files changed, 38 insertions(+)
Add irq_hpd sysfs node to displayport driver. This allows the userspace
to subscribe to irq events similar to how it can subscribe to changes in
hpd.
irq_hpd is read only and returns the number of irq events generated since
driver probe. pending_irq_hpd is added so that a sysfs_emit can be
generated if the HPD high event belonging to the same status message
is delayed until a successful configuration.
Signed-off-by: RD Babiera <rdbabiera@google.com>
Reviewed-by: Badhri Jagan Sridharan <badhri@google.com>
---
Changes since v1:
* fixed bracket styling error
---
.../testing/sysfs-driver-typec-displayport | 10 +++++++
drivers/usb/typec/altmodes/displayport.c | 28 +++++++++++++++++++
2 files changed, 38 insertions(+)
diff --git a/Documentation/ABI/testing/sysfs-driver-typec-displayport b/Documentation/ABI/testing/sysfs-driver-typec-displayport
index 256c87c5219a..314acd54e13e 100644
--- a/Documentation/ABI/testing/sysfs-driver-typec-displayport
+++ b/Documentation/ABI/testing/sysfs-driver-typec-displayport
@@ -62,3 +62,13 @@ Description:
by VESA DisplayPort Alt Mode on USB Type-C Standard.
- 0 when HPD’s logical state is low (HPD_Low) as defined by
VESA DisplayPort Alt Mode on USB Type-C Standard.
+
+What: /sys/bus/typec/devices/.../displayport/irq_hpd
+Date: June 2025
+Contact: RD Babiera <rdbabiera@google.com>
+Description:
+ IRQ_HPD events are sent over the USB PD protocol in Status Update and
+ Attention messages. IRQ_HPD can only be asserted when HPD is high,
+ and is asserted when an IRQ_HPD has been issued since the last Status
+ Update. This is a read only node that returns the number of IRQ events
+ raised in the driver's lifetime.
diff --git a/drivers/usb/typec/altmodes/displayport.c b/drivers/usb/typec/altmodes/displayport.c
index b09b58d7311d..7f9f1f98f450 100644
--- a/drivers/usb/typec/altmodes/displayport.c
+++ b/drivers/usb/typec/altmodes/displayport.c
@@ -65,6 +65,13 @@ struct dp_altmode {
enum dp_state state;
bool hpd;
bool pending_hpd;
+ u32 irq_hpd_count;
+ /*
+ * hpd is mandatory for irq_hpd assertion, so irq_hpd also needs its own pending flag if
+ * both hpd and irq_hpd are asserted in the first Status Update before the pin assignment
+ * is configured.
+ */
+ bool pending_irq_hpd;
struct mutex lock; /* device lock */
struct work_struct work;
@@ -151,6 +158,7 @@ static int dp_altmode_status_update(struct dp_altmode *dp)
{
bool configured = !!DP_CONF_GET_PIN_ASSIGN(dp->data.conf);
bool hpd = !!(dp->data.status & DP_STATUS_HPD_STATE);
+ bool irq_hpd = !!(dp->data.status & DP_STATUS_IRQ_HPD);
u8 con = DP_STATUS_CONNECTION(dp->data.status);
int ret = 0;
@@ -170,6 +178,8 @@ static int dp_altmode_status_update(struct dp_altmode *dp)
dp->hpd = hpd;
dp->pending_hpd = true;
}
+ if (dp->hpd && dp->pending_hpd && irq_hpd)
+ dp->pending_irq_hpd = true;
}
} else {
drm_connector_oob_hotplug_event(dp->connector_fwnode,
@@ -177,6 +187,10 @@ static int dp_altmode_status_update(struct dp_altmode *dp)
connector_status_disconnected);
dp->hpd = hpd;
sysfs_notify(&dp->alt->dev.kobj, "displayport", "hpd");
+ if (hpd && irq_hpd) {
+ dp->irq_hpd_count++;
+ sysfs_notify(&dp->alt->dev.kobj, "displayport", "irq_hpd");
+ }
}
return ret;
@@ -196,6 +210,11 @@ static int dp_altmode_configured(struct dp_altmode *dp)
connector_status_connected);
sysfs_notify(&dp->alt->dev.kobj, "displayport", "hpd");
dp->pending_hpd = false;
+ if (dp->pending_irq_hpd) {
+ dp->irq_hpd_count++;
+ sysfs_notify(&dp->alt->dev.kobj, "displayport", "irq_hpd");
+ dp->pending_irq_hpd = false;
+ }
}
return dp_altmode_notify(dp);
@@ -707,10 +726,19 @@ static ssize_t hpd_show(struct device *dev, struct device_attribute *attr, char
}
static DEVICE_ATTR_RO(hpd);
+static ssize_t irq_hpd_show(struct device *dev, struct device_attribute *attr, char *buf)
+{
+ struct dp_altmode *dp = dev_get_drvdata(dev);
+
+ return sysfs_emit(buf, "%d\n", dp->irq_hpd_count);
+}
+static DEVICE_ATTR_RO(irq_hpd);
+
static struct attribute *displayport_attrs[] = {
&dev_attr_configuration.attr,
&dev_attr_pin_assignment.attr,
&dev_attr_hpd.attr,
+ &dev_attr_irq_hpd.attr,
NULL
};
base-commit: e04c78d86a9699d136910cfc0bdcf01087e3267e
--
2.50.0.rc2.761.g2dc52ea45b-googOn Mon, Jun 23, 2025 at 08:49:45PM +0000, RD Babiera wrote:
> Add irq_hpd sysfs node to displayport driver. This allows the userspace
> to subscribe to irq events similar to how it can subscribe to changes in
> hpd.
>
> irq_hpd is read only and returns the number of irq events generated since
> driver probe. pending_irq_hpd is added so that a sysfs_emit can be
> generated if the HPD high event belonging to the same status message
> is delayed until a successful configuration.
>
> Signed-off-by: RD Babiera <rdbabiera@google.com>
> Reviewed-by: Badhri Jagan Sridharan <badhri@google.com>
Reviewed-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
> ---
> Changes since v1:
> * fixed bracket styling error
> ---
> .../testing/sysfs-driver-typec-displayport | 10 +++++++
> drivers/usb/typec/altmodes/displayport.c | 28 +++++++++++++++++++
> 2 files changed, 38 insertions(+)
>
> diff --git a/Documentation/ABI/testing/sysfs-driver-typec-displayport b/Documentation/ABI/testing/sysfs-driver-typec-displayport
> index 256c87c5219a..314acd54e13e 100644
> --- a/Documentation/ABI/testing/sysfs-driver-typec-displayport
> +++ b/Documentation/ABI/testing/sysfs-driver-typec-displayport
> @@ -62,3 +62,13 @@ Description:
> by VESA DisplayPort Alt Mode on USB Type-C Standard.
> - 0 when HPD’s logical state is low (HPD_Low) as defined by
> VESA DisplayPort Alt Mode on USB Type-C Standard.
> +
> +What: /sys/bus/typec/devices/.../displayport/irq_hpd
> +Date: June 2025
> +Contact: RD Babiera <rdbabiera@google.com>
> +Description:
> + IRQ_HPD events are sent over the USB PD protocol in Status Update and
> + Attention messages. IRQ_HPD can only be asserted when HPD is high,
> + and is asserted when an IRQ_HPD has been issued since the last Status
> + Update. This is a read only node that returns the number of IRQ events
> + raised in the driver's lifetime.
> diff --git a/drivers/usb/typec/altmodes/displayport.c b/drivers/usb/typec/altmodes/displayport.c
> index b09b58d7311d..7f9f1f98f450 100644
> --- a/drivers/usb/typec/altmodes/displayport.c
> +++ b/drivers/usb/typec/altmodes/displayport.c
> @@ -65,6 +65,13 @@ struct dp_altmode {
> enum dp_state state;
> bool hpd;
> bool pending_hpd;
> + u32 irq_hpd_count;
> + /*
> + * hpd is mandatory for irq_hpd assertion, so irq_hpd also needs its own pending flag if
> + * both hpd and irq_hpd are asserted in the first Status Update before the pin assignment
> + * is configured.
> + */
> + bool pending_irq_hpd;
>
> struct mutex lock; /* device lock */
> struct work_struct work;
> @@ -151,6 +158,7 @@ static int dp_altmode_status_update(struct dp_altmode *dp)
> {
> bool configured = !!DP_CONF_GET_PIN_ASSIGN(dp->data.conf);
> bool hpd = !!(dp->data.status & DP_STATUS_HPD_STATE);
> + bool irq_hpd = !!(dp->data.status & DP_STATUS_IRQ_HPD);
> u8 con = DP_STATUS_CONNECTION(dp->data.status);
> int ret = 0;
>
> @@ -170,6 +178,8 @@ static int dp_altmode_status_update(struct dp_altmode *dp)
> dp->hpd = hpd;
> dp->pending_hpd = true;
> }
> + if (dp->hpd && dp->pending_hpd && irq_hpd)
> + dp->pending_irq_hpd = true;
> }
> } else {
> drm_connector_oob_hotplug_event(dp->connector_fwnode,
> @@ -177,6 +187,10 @@ static int dp_altmode_status_update(struct dp_altmode *dp)
> connector_status_disconnected);
> dp->hpd = hpd;
> sysfs_notify(&dp->alt->dev.kobj, "displayport", "hpd");
> + if (hpd && irq_hpd) {
> + dp->irq_hpd_count++;
> + sysfs_notify(&dp->alt->dev.kobj, "displayport", "irq_hpd");
> + }
> }
>
> return ret;
> @@ -196,6 +210,11 @@ static int dp_altmode_configured(struct dp_altmode *dp)
> connector_status_connected);
> sysfs_notify(&dp->alt->dev.kobj, "displayport", "hpd");
> dp->pending_hpd = false;
> + if (dp->pending_irq_hpd) {
> + dp->irq_hpd_count++;
> + sysfs_notify(&dp->alt->dev.kobj, "displayport", "irq_hpd");
> + dp->pending_irq_hpd = false;
> + }
> }
>
> return dp_altmode_notify(dp);
> @@ -707,10 +726,19 @@ static ssize_t hpd_show(struct device *dev, struct device_attribute *attr, char
> }
> static DEVICE_ATTR_RO(hpd);
>
> +static ssize_t irq_hpd_show(struct device *dev, struct device_attribute *attr, char *buf)
> +{
> + struct dp_altmode *dp = dev_get_drvdata(dev);
> +
> + return sysfs_emit(buf, "%d\n", dp->irq_hpd_count);
> +}
> +static DEVICE_ATTR_RO(irq_hpd);
> +
> static struct attribute *displayport_attrs[] = {
> &dev_attr_configuration.attr,
> &dev_attr_pin_assignment.attr,
> &dev_attr_hpd.attr,
> + &dev_attr_irq_hpd.attr,
> NULL
> };
>
>
> base-commit: e04c78d86a9699d136910cfc0bdcf01087e3267e
> --
> 2.50.0.rc2.761.g2dc52ea45b-goog
--
heikki
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